Member postings for Clive Steer

If I remember correctly there is limited parking available at Soper Hall and although there are Morrisons and Waitrose carparks nearby these may have conditions attached. So anyone knows where parking may be found that would be helpful.

CS

Thanks Michael for the link to the excellent article about magnetic scales and their sensors which has helped me understand some of the finer points of their operation.

I only use magnet scales for short distances (<300mm) where the magnetic strip can be well supported and distance between the head and tape accurately maintained. For longer distances I always use glass scales which can tolerate a larger amount of tracking error. However in all cases the read head does have to be very rigidly mounted to ensure there is no flexing due to connection cable tension/movement.

Newall sell an excellent and compact Magnetic DRO system but they are not cheap.

CS

Unfortunately the bed plate and flywheel were not in the box. However I do have some 15mm thick Ali plate which although will need some chopping our won't need facing.

CS.

Taking up Joseph's point the cable from the inverter to the motor should have an earthed screen bonding the motor casing to the inverter and to the machine to prevent radiated EM noise .

CS

As far as I recall the EM noise emissions allowed for industrial installed equipment is far more that that allowed for Laboratory/Domestic installation. So Newton-Tesla may say their kit is designed for industrial installation. To meet domestic requirements they may say you need to buy a filter. An extremely crude filter can be made by simply winding the mains lead around a lump of steel rod and this may be sufficient to prove that conducted EM noise is causing the issue with the DRO.

CS

Hi Paul

Many thanks and you are spot on with the model. I went onto their site and looked at the casting which bear the same numbers as those on the parts I have. I'm not a steam model builder so I'll probably sell the kit on to someone more likely to complete it in the manner it deserves.

Clive

I've been given, what appears to be, a kit of castings and materials to make a static engine. Unfortunately there were no drawings or document identifying the model name or supplier. I've done a quick search on the internet and found it is not a Stuart model so I'm hoping someone may be able me identify it.

My advice would be to buy the biggest lathe your budget or space allows as you can always do small on a big lathe but not the other way around. Then find someone who has the lathe you are thinking of getting and ask what idiosyncrasies/problems the lathe has. Treat the lathe as a system so what you need to power it and the ease of obtaining tooling etc should also be considered. Do the leg work to see as many lathe types as you can including asking professional machine shops what they like best.

If you choose to buy a ex-industrial machine bear in mind that it will be 440V 3 phase so will need a phase converter, inverter or new motor to work from a domestic supply. The bigger the lathe the more difficult it will be to power it without special electrical facilities. Bear in mind an ex-industrial machine may have been worked hard but having said that they are designed for that so, unless abused, may still have plenty of lift left in it.

A good machine may be expensive to buy but should also be easy to sell.

CS

Hi David

As a retire electronics design engineer I wouldn't mind checking it out to see if the unit has a fault or is not correctly designed.

CS

Aircraft crimp connectors can be bought from LASaero. The knife disconnect terminals are good for connections that only need to be disconnected occasionally.

Farnell sell the Deutsch range of multi-pin connectors often found in car wiring harnesses. These are well sealed but current carrying capacity is not high.

CS

Farnell or RS components sell good quality connectors, wire, crimps and crimping tools although they are not cheap.

Aircraft component suppers such as LAS sell aviation quality connectors but these will be much more expensive.

CS

For the man in the street I think the best method of making reliable and consistent electrical connections is by using crimp connectors. The high pressures generated when crimping cold welds the copper wire strands together and to the crimp terminal to form a gas tight joint which prevents joint corrosion. Using heat shrink tube to cover the joint should prevent water/salt etc wicking up the wire strands.

The flux needed for soldering can cause wire corrosion and the heat needed can cause the copper strands to become hardened and cause failure when flexed.

CS

If there is a large price difference, per kWh, between gas and electricity maybe one should install a gas fuelled ICE generator. To further improve cost efficiency the waste heat from the ICE can be fed directly to the central heating system and/or to the air source heat pump. If one has solar panels and a battery all the better to reduce gas usage on sunny days and cover periods of high demand. If one can be self sufficient in electricity then the standing charge may only have to be paid for the supply of gas making further savings.

Although the Utilities sell the advantages of centralised resource and distribution the come a time when the cost model isn't the best. First rule of business. When you are the only supplier of a commodity in demand you can charge what you like.

Clive S

As far as I recall using a pressurised CH system allows the boiler to be installed anywhere and operating between 1-2 bar increases the boiling point of the water which prevents heat exchanger hot spots and noise.

Refilling the system from pressurised mains water can introduce dissolved Oxygen so inhibitor should be added every time you refill. In my loft I have a vent valve to release any gas in the system but I also use it to suck in inhibitor when I do a partial drain down before a refill.

Ideally any top up water should be boiled to get rid of dissolved gasses and then pumped into the system along with inhibitor but this not a trivial exercise.

Clive S

RDG tools did supply BCA adaptors with blank ends, several of which I purchased for mounting slitting saws and one adapted I made into an ER16 collet holder. Unfortunately RDG only appear to now stock adaptors with a threaded nose.

I have an ER16 adaptor that I think fits an EMCO lathe threaded spindle which is 14mm x 1mm. If used with an RDG adaptor it would reduce headroom by 50 mm .

Having a new spindle made for the BCA with a ER16/20 nose, although not trivial, would solve the problem of cutter holding and headroom. If I remember correctly the BCA spindle is of relatively simple design.

Clive S

Many gas boiler controllers detect the presence of the burner/pilot flame by applying 250V AC mains to a probe in the flame. A flame acts as a weak rectifier and so will generate a small DC voltage which the controller checks before opening the main burner gas valve.

The flame detection circuit may not work if the generators output waveform is non-sinusoidal or if the output is noisy or not grounded correctly. The flame detection circuit has to be a fail safe circuit so a poor signal from the detector may be regarded as a potential failure and causes the controller to abort a start up sequence and enter a non-functional locked out state.

The start up sequence of many spark ignition gas boilers would normally begin with turning on the burner fan and proving a pressure change has occurred. After a short delay to purge any gas the pilot flame gas valve will open and ignition initiated using a spark generator for a few second. Following this flame detection is expected and if proved the main burner gas valve will be opened to admit gas to the main burner. Flame presence continues to be monitored and if lost then all gas valves are shut and the controller go to lockout.

Clive S

I'm not sure that some people understand even the basics of ensuring electrical safety.

The first rule is prevention. So at no time should anyone come into contact with a potentially lethal voltage.

If it does happen other factors will determine if the outcome is fatal or just a warning tickle or the RCD tripping if you have one. Arguing that if a machine is earthed it may make the situation worse is very questionable.

Safety improvements seem to be driven more by hindsight than foresight with train, car and aircraft safety being good examples of our failures of foresight.

Let us at least apply what hindsight has taught us.

Clive S

Most modern electrical products are considered to be stand alone devices and do not require an extra earth (supplementary bonding) either because of where they are allowed to be used or because of their design.

There have been several forum articles about users wanting to change/upgrade the electrical features of their machines which they will do without compromising electrical safety.

My main point, although I may not have explained it very well, is that an extra earth wire attached to a machine is relatively easy to do by someone with little electrical understanding and can make a machine safer if for any reason they get it wrong.

Things have changed in 50 years with site electrics needing 110V equipment and isolation transformers, houses needing RCD's and MCB's, kitchens and bathrooms having special electrical installation regulations, the re-introduction of earth stakes because gas and water pipes can't be relied on to provide an earth, the introduction of more stringent product design requirements etc.

Whatever happens in a machine by way of failure or modification just makes sure that the main bits you are likely to grab hold of are earthed.

Clive S

Edited By JasonB on 02/02/2022 11:04:36

I don't believe the specs require two earths but if the electrical safety of a machine or instruments relies on a earth being present then a single failure of that earth connection could result in the machine or instrument becoming unsafe. One way to overcome this situation is to have two earths so if one failed there is the other. However if both earth wires are hidden then you may not know that one has already failed and you're back to single failure situation. Regular testing or a method to prove the earth is present before power can be applied is possible but a visual check is relatively simple to do.

Every a domestic ring main socket outlet has two earth wires and an earth wire from the socket earth to the metal back box in case the screws don't provide good contact or get left out. Another example is a domestic metal kitchen sink is required to have second earth in case one isn't provided by the pipework.

Clive S

A quick check of IEC60204 shows there is a section on "Protective Bonding requirements, terminology and protection against electric shock" commonly called earthing by laymen.

Clive S